. you're projecting again . and not a grain of wit in your reply. Perhaps you don't know that Vitriol is an old name for sulfuric acid , aka battery acid . I shall view your future posts as acid reflux.
get a Mc Alpine DC 1 and put a plug in it . Then arrange a rope or chain connected to the setup , hang the free end on a hook screwed into the manhole near the lid. If it blocks fully you can tug the "plug" you've made (y) (y)
There is a way to plug the rodding hole - not using a test plug, but I don't want ree to abuse me so I'm keeping quiet for now. But you mention 2 manhole covers - what's the second one do ?
For the new hole hire a diamond core drill and tool to power it . You could use an sds drill IF it's got a clutch - to power the core drill. You might get a circle of render to put in the original hole.